In making an orthodontic appliance it is required that the brackets be harmonized with the dental arch of the individual patient and simultaneously made in clearly defined positions
Thus it is known from U.S. Pat. No. 3,477,128 to use brackets for this orthodontic appliance whose constructions are harmonized with the average anatomical shape and position of the individual tooth in a dental arch so that the number of required bends of the orthodontic arch wire used is substantially reduced, although the bends can never be completely eliminated.
Other known processes for additional individualizing of the brackets and thus for individual minimizing of the required wire bending require in part great expense, are connected with expensive manipulations requiring a high dexterity or leave the accuracy of the required manipulations to what can be determined by eye.
In the process as described in the U.S. Pat. No. 4,014,096 the bracket openings are cut individually which is rather costly.
In U.S. Pat. No. 4,160,322 a process of the above-described type for individualization of the brackets is disclosed in which the brackets are held directly on the idealized model of the dental arch by a template. The template is curved according to the orthodontic arch wire curvature. A casting of the replica of the idealized model is made. This has the disadvantage that the process on the one hand is not suitable for setting brackets, which are characterized as "molar-tubes", which must be used for molars and on the other hand the casting acting for transfer of the brackets from the idealized model to the patient teeth can grip or embrace the brackets in the vicinity of the template only very loosely and with weak retention for want of working room.
A process and apparatus of the above-described kind is also known from U.S. Pat. No. 3,949,478. However the process requires a great deal of skill and precision of measurement by eye and the process requires a very complicated apparatus for positioning.
The European Patent Application Publication 0 084 443, discloses a process and an apparatus of the above-described kind in which, before the casting of the patient's dental arch, orienting structures are provided at the positions where the attachment is to be made on the patient's dental arch by adhesive material or platelets which are glued on.
The orienting structures serve for later positioning and attachment of the individualized brackets at the bases.
The individualization of the brackets is effected by lining the bases of the brackets, which are held on the tooth replicas of the idealized model by an orthodontic arch wire fixed by a retainer or holder. A disadvantage of this process is that for three-dimensional arrangement of the brackets on the patient's dental arch a structure in the vicinity of the attachment positions of the brackets is used which can be lost during the orthodontic treatment so that no reproducibility is possible.
Another disadvantage is that on individual lining of the bracket bases, the idealized model is pushed on the brackets held by the wire, so that the process is unsuitable for a jaw shape in which the dental arch curvature in the vicinity of the second molar is of equal width or smaller than that in the vicinity of the first molar
Finally a process and apparatus for carrying out that process are known from U.S. Pat. No. 4,183,141, in which a bracket can be positioned on the tooth at a certain position by a bracket support. The bracket is pressed on the tooth or on the tooth replica by a pushing device, whereby the tooth surface forms a stop for the bracket during the pressing motion.
The disadvantage of this apparatus is that the direct contact of the bracket on the tooth surface determines the position of the slot-like bracket openings tangential to the tooth surface so that no compensation is effected for different tooth thicknesses and rotation requirements and numerous bends and angulations are required of the orthodontic arch wire fitted in the bracket openings.